They sell classroom text books at most book stores, go in and order (as they likely won't have any in stock) one of these. I don't recall the exact name of mine but its some 700 pages of basic "how stuff works" with cars. I bought it souly in the case to refresh myself or learn something I don't already know. Or you can take Automotive classes, generally a high school or community college will offer these to students.
Changing the oil is extremely simple.